1. Field of the Invention
This invention relates to a boring bar holder and metal cutting insert having means for relocation or indexing the cutting insert with precision at the angle and location it was before removal or before another insert was removed and replaced.
2. Description of the Prior Art
In the formation of bores in metal parts a machine tool or lathe is usually used. The machine tool includes a work spindle within which there is a combined holder or boring bar and cutting insert. If it was necessary to replace the cutting insert, the whole unit was removed and a new unit inserted. With no way to index it, it was impossible to reinsert the unit exactly as it was.
Next, a manufacturer devised the idea of forming a separate holder or boring bar that was inserted within the spindle. A cutting insert was then separately fabricated and it could be inserted into the boring bar and replaced by a new cutter when the old one become dull. However, the only type of indexing that was done to try to achieve a position close to the previous insert was by flattening one side of the inset and provide a set screw through the boring bar to bias against the flat surface. However, this was not accurate because the set screw only engaged a small area of the flat and further there was no assurance that the end of the insert would engage the back wall of the insert hole to assure stability of the insert during rotation and cutting.
Thus prior to the present invention there were no boring bar insert combinations to achieve the desired exact placement or indexing nor the locking of the insert where movement is prevented during use.